JP2002110167A - Lithium oxide material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode material at low cost which discloses layers of the cathode material made from lithium and transition metal oxide, replaces a large amount of manganese and provides a competitive electrical chemical characteristic and a good thermal safe characteristic. SOLUTION: A single phase cathode material used in an electrical chemical battery is expressed by formula Li[LixCoyA1-x-y]O2. (In the formula, A expresses [MnzNi1-z], x expresses a value having a range of approximately 0.00-0.16, y expresses a value having a range of approximately 0.1-0.30, z expresses a value having a range of approximately 0.40-0.65, Lix is included in a transition metal layer of the structure; and/or the material includes a stratified R-3m crystal structure having a c/a ratio of approximately 1.012 or more.).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to lithiated oxides having a well-developed layered crystal structure for use as cathode materials and to a process for producing such oxides.

[0002]

BACKGROUND OF THE INVENTION Rechargeable lithium batteries have commercial advantages due to high energy and power density, and long cycle life. Lithium ion batteries (ie, batteries that do not use metallic lithium as the anode) have replaced lithium batteries. The reason for this is that when using lithium metal as the anode,
Long cycles are problematic. Most rechargeable lithium ion batteries use an anode material that is free of lithium metal, such as a carbon or tin containing material. This requires that the cathode contain lithium that can be extracted during the first charge and during hundreds or more charge and discharge cycles. Prior to the introduction of lithium-ion batteries, all well cycled materials, including sulfides, were nominated for the cathode.
Since the introduction of lithium-ion batteries, material choices have practically dropped dramatically.

The most interesting cathodes for rechargeable lithium ion batteries are the spinel Li
A lithium transition metal oxide such as _{1 + x} Mn _2-x O ₄ (and its variants) and LiCoO ₂ . Spinel L
_{i 1 + x Mn 2-x} O 4 is inexpensive, do not contain harmful substances. However, its use is limited. The reason is that the capacity of materials that cycle well is only about 115 mA
This is because h / g. Further, retention of capacity during high temperature cycling (eg, 55 ° C. cycling) is not sufficient. LiCoO ₂ cycles well, about 140m
Although having a capacity of Ah / g, Co is toxic and expensive. Li ₁ + _{x Mn} as _{2-x O 4} and some of the prospective alternative to LiCoO ₂ is a ₂ group material LiNiO. Nickel is less toxic, less toxic than Co, and has lower cocto. Further, LiNiO ₂ is converted to LiC
It has a larger reversible capacity than oO ₂ .

[0004] LiNiO₂And LiCoO₂Is α-N
aFeO₂Layered material having a mold structure (space group R-3m)
It is. Layered materials are interesting materials for cathodes.
You. The reason is that the layered structure allows lithium to diffuse quickly
Because it is done. In this structure, octahedral by oxygen
Layer of transition metal (MO₂Sheet)
Are separated by lithium cations in the lithium layer.
Its general formula is LiMO ₂It can be expressed as. This specification
Wherein the general formula is Li [M] O₂Or {LiM}
[M] O₂Will often be described. Where:
[M] represents all cations remaining in the transition metal layer.
And {M} represents the non-lithium cation in the lithium layer
You. Many prior art LiNiO₂In the base material,
The memory layer is partially filled with transition metal ions. example
For example, nickel-rich LiNiO₂Which is ｛L
i_0.9Ni_0.1｝ [Ni] O₂Can be described. Caso
One of the most promising applications of the card is to fully layer it.
Material. That is, located at the lithium site
It is a material with little or no transition metal M. This
Well-ordered structure is lithium intercalation
Quick and deintercalation.

It is difficult to tune LiNiO ₂ to maintain an acceptable capacity for long cycles. LiNi
O ₂ materials also lead to irreversible capacity loss in the first cycle generally. That is, less lithium can re-enter during the first discharge than lithium during the first charge. Large irreversible capacity is undesirable for practical applications. Good capacity retention and low irreversible capacity are associated with a well-layered crystal structure. An ideally layered crystal structure has a large c: a ratio and a small amount of transition metal not located at a lithium site. However, in practice, it is difficult to prepare a sample having only a small amount of Ni at the Li layer site. The amount of Ni at the lithium site can be estimated from the improvement of the Rietveld method of the X-ray diffraction data. Or, Solid
Dahn et al. In State Ionics 44 (1990) 87 define an R factor that is sensitively related to Ni concentration at lithium sites. R is defined as the ratio of the integrated intensity of the 101, 006, and 102 peaks of the diffraction pattern of the layered material having the R-3m structure. Many of the disclosed prior art techniques show how to prepare LiNiO ₂ materials with low Ni content that are not located at lithium sites. In other words, those techniques use LiN having a small R value.
Attempts have been made to prepare iO ₂ materials, but these methods have not completely solved the problem or are not economical.

Another fundamental problem with LiNiO ₂ materials is that
This material becomes very reactive when overcharged, that is, when charged to a voltage such that more than about 60% of the nickel is oxidized from the 3+ to the 4+ state. is there. In a large battery, the overcharged cathode slowly decomposes, generating more heat that the battery can release to the environment. This accelerates the decomposition reaction, which ultimately allows the battery to dissipate heat by exploding, igniting, or venting. In fact, large batteries cannot use LiNiO ₂ as a cathode. The reason for this is that they try to escape the heat and are therefore dangerous.

[0007] Solid State Ionics
In 69 (1994) 265, Dahn et al.
iNiO ₂ is described as dangerous because Li _1-x NiO ₂ contains very reactive Ni ions. The cathode reacts to the Solid Stat
e Aronics in Ionics 109 (1998) 295
Rock salt type Li _x Ni _1-x as disclosed by ai et al.
O tends to form. In the rock salt structure, Ni is in a more favorable low average valence state. This reaction involves the release of oxygen that can react with the electrolyte.

[0008] LiNiO ₂ doped with a material having low or no reactivity can be a reactive Ni ⁴⁺ diluted material. It shows that replacing Ni ions with other cations improves electrochemical performance in some cases. U.S. Pat. No. 5,750,288 (Rayovac) issued May 12, 1998 replaces up to 30% of Ni with a non-transition metal element selected from the group of Al, Ga, Sn and Zn. By doing
Modification of LiNiO ₂ is described. J. E
electrochem. Soc. 142 (1995) 4
033 by Ohzuku et al. With Al and Electrochemical an.
d Solid State Letter (199
8) The Gao et al. 117 doping with Mg _1/2 Ti _1/2 shows that substitution improves the safety of the LiNiO ₂ type material to some extent.

Replacement of nickel using cobalt fractionation
(For example, Li [Ni _1-xCo_x]
O₂Where x is about 0.2 to 0.3. ), Good
It can be a material with good electrochemical properties. like this
Materials are, for example, J.I. PowerSources 43 /
44 (1993) 595, described by Delmas et al.
Have been. However, LiNiO₂Safety issues related to
The subject is not completely solved. This is
Electroc in Seattle, May 2-6
Chemical Society's 195th Meeting
Proceedings, Abstract43
Paulsen and Dahn. Further
In addition, the replacement of nickel with cobalt is LiNiO₂To
The cost of the material is higher.

It is expected that the use of manganese as a dopant for the LiNiO ₂ -based compound will be advantageous. Since manganese is inexpensive and danger-free, LiNiO
_The use of large amounts of Mn for the _two cathodes would be desirable not only for safety considerations, but also for price.

LiNiO₂Of Ni by manganese
That is, Solid State Ionics 57
(1992) 311 described by Dahn et al.
You. According to this report, LiNiO₂Is replaced with manganese
And Li [Ni_1-xMn _x] O₂And the maximum of x
The replacement limit is about 0.5. Where x> 0.5
This material is not a single phase, but in the rock salt structure, Li
₂MnO₃And Li _yNi_1-yIn a phase mixture containing O
is there. However, LiNiO with a large amount of manganese
₂Is especially Li [Ni_1/2Mn_1/2] O₂Is enough
It states that the cycle could not be performed.

US Pat. No. 5,264,201, issued Nov. 23, 1993 (Dahn et al.), Discloses LiNi
Describes a process for producing a _1-y M _{y O 2,} where, M can be a Co, Fe, Cr, Ti, Mn or V, y is about 0.2 less than (where M is C
With o, there is an exception that y is less than about 0.5. ). In this method, a material substantially free of lithium hydroxide or lithium carbonate, and unsubstituted LiNiO
It is intended to provide materials with improved cycle capacity over _two . However, according to this disclosure, the improved cycle capacity is that up to 20% of the Ni is Co, Fe, Cr, T
It is described as being maintained only when substituted by i, Mn or V (or substituted by up to 50% for Co), and there is no disclosure of preparation of a compound having a higher substitution amount.

US Pat. No. 5,370,948 (Matsushita) issued on Dec. 6, 1994 includes LiNi
(Wherein, x is from an _{0.05~0.45.) 1-x Mn x} O 2 process for producing are described. Mn is 50%
Although compositions have been disclosed in which Ni has been substituted, the crystal structure of this composition is not sufficiently layered. This is evidenced by the X-ray diffraction data in this disclosure. This data shows a single diffraction peak in the 63-66 degree 2-theta region, described as the 110 peak. Layered rhombohedral compounds with c / a ratios greater than 1 show two peaks in this region (hexagonal 108 and 110 peaks). In addition, this compound
It is evident from the X-ray diffraction data that the higher the amount of Mn substitution, the lower the stratification, the higher the Mn substitution (eg 40% Mn). There is also evidence for the formation of a _second phase (perhaps Li ₂ MnO ₃ ) with data for 40% Mn substitution.

US Patent No. 5,626,635 (Matsushita) issued May 6, 1997 includes:
LiNi _1-y M _{y O 2} compounds (here, M is either Co or Mn.) Process for producing it are described. Preferably M is Mn and y is 0.3 or less. According to this disclosure, if more than 30% of Ni is replaced by Mn, crystal growth becomes difficult and the second
When used as a cathode in a lithium battery, the material will cycle poorly. The limit temperature recommended by the method for producing this material is between 600 and 800 degrees. According to this disclosure, a material containing Mn substituted for Ni is 80%.
When heated beyond 0 degrees, Mn that is not located at the Li site in the crystal structure becomes disordered, resulting in deterioration of discharge capacity and cycle life.

US Pat. No. 5,393,622 (Matsushita) issued February 28, 1995 includes Li _y Ni _1-x Mn _x O _2, where 0 <x ≦
0.3 and 1 ≦ y ≦ 1.3. ) Are described. This method comprises the steps of Li salt, Mn oxide,
Or a multi-step solid state reaction using carbonate and Ni carbonate or hydroxide. The materials were adjusted with varying amounts of lithium. It shows that additional Li (y> 1) is inserted into the layered Mn-doped LiNiO ₂ . However, it was observed that up to 0.3 moles of Mn could be introduced into the crystal structure. When x was greater than 0.3, a decrease in crystallinity was observed, and when x was 0.4, a Mn spinel peak representing the formation of the second phase appeared in the X-ray diffraction data. The material corresponding to x up to 0.3 has a c / a of about 1.010 (= c _hex / (24 ^0.5 a
_hex )) ratio and the c _hex axis is generally "14.15 <c <14.24 angstroms". That is, it is not sufficiently layered to be achieved by the invention disclosed herein.

US Patent No. 6,045,771 issued April 4, 2000 (FujiChemical I)
ndustry Co. ) _Includes Li _y-x1 Ni
In _{1-x 2 M x O 2} ( where, M is Al, Fe, Co, M
represents one element selected from the group consisting of n and Mg, x = x ₁ + x ₂ , 0 <x ₁ ≦ 0.2, 0 <x ₂ ≦ 0.
5, 0 <x ≦ 0.5, 0.9 ≦ y ≦ 1.3. ) Is disclosed. The disclosed compounds include LiNi
_{1-x Mn} x _{O 2} (wherein, x is up to 0.4.)
However, when the amount of Mn increases, the increase in capacity gradually stops.

Furthermore, Japanese Patents JP 3047693 and JP 3042128 (Matsushima) disclose a battery composed of a LiNi _1-x M _x O ₂ material manufactured by a special method. However, when the amount of Mn is 0.1.
Above 3, the capacity is greatly reduced. Therefore, a composition of 0 <x <0.3 is preferable.

European Patent Application EP 0 918 041
(Fuji Pharmaceutical Co., Ltd.) has Li _y Ni _1-x Co
_x1 M _x2 O ₂ materials have been disclosed (here, 0.
9 ≦ y ≦ 1.3, 0 <x ≦ 0.5, 0 <x ₁ <0.5, x
₁ + x ₂ = x, and when M is Mn, 0 <x ₂ ≦ 0.3
It is. ). Only one material containing Mn is disclosed, where x ₂ = 0.05. In addition, European Patent Application EP 0 944 125 includes Ni,
Disclosed is an oxide of a lithium metal compound containing a combination of Co and Mn. All compounds described have at least 49% Ni (as a percentage of total Ni + Co + Mn) and up to 40% Mn (Ni
+ Co + Mn).

Further, a combination of Ni, Co and Mn is described in European Patent Application EP 0 782 206 (Japan Stor
age Battery Company). But M
When the amount of n exceeded 30% (as a percentage of total Ni + Co + Mn), a significant decrease in battery capacity was seen. Therefore, a preferred composition is that Mn is 3
This is the case when less than 0%. Also, it was considered that the addition of Al was preferable for improving the temperature safety characteristics.

In short, the possible benefits of replacing large amounts of Mn with LiNiO ₂ , often discussed in the prior art, indicate that materials with large amounts of Mn substituted exhibit acceptable electrochemical properties. Is not shown. This is generally possible layer properties of the crystal structure is low, or LiNiO _2, manganese is large, may be related to their tendency to phase separation in the multilayer mixture.

[0021]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithiated oxide material having a well-developed layered crystal structure, to reduce or overcome at least some of the above problems, or to provide a useful alternative. An object of the present invention is to provide a disclosure comprising:

[0022] Other objects of the present invention will become apparent from the following disclosure, given by way of example only.

[0023]

The single-phase cathode material of the present invention is Li [Li _x Co _y A _1-xy ] O ₂ (wherein
A ₌ represents a _{[Mn z Ni 1-z]} , 0.4 ≦ z ≦ 0.6
5, 0 <x ≦ 0.16 and 0.1 ≦ y ≦ 0.30. ) Wherein additional lithium x is included in the transition metal layer of the structure. Preferably, said material is:
It is a single-phase, well-developed layered R-3m crystal structure with a c / a ratio greater than 1.012 (where the ratio is C _hex / 24 ^1/2 a _hex ).

Preferably, 0.05 ≦ x ≦ 0.10, y
Is about 0.16 and z is about 0.50.

The present invention relates to a method for producing a material having the following composition.
And the composition is Li [Li _xCo_yA
_1-xy] O₂(Where A = [Mn_zNi_1-z]
And 0.4 ≦ z ≦ 0.65, 0 ≦ x ≦ 0.16, and
0.1 ≦ y ≦ 0.30) and the material is 1.012
Single-phase, well-developed layered structure with higher c / a ratio
R-3m crystal structure (where the ratio is C
_hex/ 24^1/2a_hexIt is. ), Additional Litchi
X is included in the transition metal layer of the structure, the method comprising:
Is a mixture of metal cations containing Ni, Mn, and Co
Preparing a precursor having a stoichiometric amount of
Mix with Li source and react the resulting mixture at high temperature
It is comprised including that. Preferably, the precursor is
In an oxygen-containing atmosphere, a temperature in the range of
Heated at temperature. Also, this temperature is almost 900 ° C
Temperatures in the range of ~ 1000C are preferred, at least 12
Time is preferred.

Preferably, said precursor is a mixture of metal hydroxides.

Preferably, the mixture of metal hydroxides is obtained by coprecipitation from a solution containing Ni, Mn and Co.

Alternatively, the precursor is a mixture of metal oxides represented by M ₃ O ₄ (where M represents a combination of Ni, Mn, and Co).

Preferably, said M ₃ O ₄ is prepared from a mixture of metal hydroxides. Alternatively, the precursor is
It is a mixture of metal oxides represented by MO (where M represents a combination of Ni, Mn, and Co).

Preferably, M is a mixture of metal oxides.
O is prepared from a mixture of metal hydroxides.

Alternatively, the mixture of the metal precursor is L
(wherein, M represents a combination of Ni, Mn, and Co, x represents. about 1) i _x MO ₂ is a mixture of a metal oxide represented by. Preferably, the lithium source is L
i ₂ CO ₃ .

The present invention relates to a method for producing a material having the following composition.
And the composition is Li [Li _xCo_yA
_1-xy] O₂(Where A = [Mn_zNi_1-z]
Where 0.4 ≦ z ≦ 0.65, 0 <x ≦ 0.16, and
0.1 ≦ y ≦ 0.30) and the material is 1.012
Single-phase, well-developed layered structure with higher c / a ratio
R-3m crystal structure (where the ratio is C
_hex/ 24^1/2a_hexIt is. ), Additional Litchi
X is included in the transition metal layer of the structure, the method comprising:
Mixes powder of metal oxide, and said metal oxide is N
i, Mn, Co and lithium.
Mill with a mill to produce a precursor oxide, the precursor
The method includes heating the oxide.

[0033] Preferably, the metal oxide is selected such that the total amount of lithium and oxygen is close to the stoichiometric amount required in the final lithiated oxide material.

More preferably, the heating of the precursor oxide or the reaction of the mixture is performed in an oxygen-containing atmosphere at a temperature in the range of about 500 ° C. to 1000 ° C.

Preferably, this temperature is between about 900 ° C.
In the range of 1000 ° C., preferably at least 1
Performed for 2 hours.

Further, the present invention relates to a method for producing a lithiated oxide material having a layered crystal structure, which is as described above, and is shown in the following examples and drawings. .

The present invention further provides lithiated oxide materials having a layered crystal structure, which are as described above and are shown in the following examples and figures. Further, the present invention provides a cathode for use in a secondary lithium ion electrochemical cell, said cathode comprising as active material a lithiated oxide material as described above.

Further, the present invention relates to a lithium intercalation anode, a suitable non-aqueous electrolyte containing a lithium salt, a cathode containing a lithiated oxide material as described as an active material, and a method for forming a cathode between an anode and a cathode. A second lithium ion electrochemical cell having a separator is provided.

The invention further provides for the use of the lithiated oxide materials described in the manufacture of cathode and / or secondary lithium ion electrochemical cells.

Other aspects of the invention will become apparent from the following description and drawings, given by way of example only.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS While the present invention may be embodied in many different forms, there are certain embodiments described in the drawings and specification that are disclosed for an understanding of the invention. Is not limited.

The present invention discloses a layered lithium / transition metal oxide cathode material that replaces large amounts of manganese to provide a low cost, with competitive electrochemical and good thermal safety properties. A cathode material is provided.

The material of the invention is fully layered,
A small amount of transition metal is misplaced in the lithium site,
It has a high c: a ratio greater than 1.012. The c: a
The ratio is the hexagonal lattice constant c divided by the hexagonal lattice constant a
^Is divided by 24 ^1/2 . A high c: a ratio corresponds to a small rhombohedral angle α.

The material of the present invention is Li [Mn _z N
i _1-z ] O ₂ . An important aspect of the present invention is that z is as large as possible to reduce manufacturing costs and to achieve good thermal safety properties;
Preferably, it is at least greater than 0.4.
However, the prior art has consistently used z ≧ 0.3 when used as the cathode active material in secondary lithium batteries.
No. 4 discloses the electrochemical properties of the materials. In particular, as compared with the composition when z <0.4, the capacity is reduced, and the cycle stability is inferior. These problems are solved by the following aspects of the present invention.

According to the present invention, Li [Mn _z N
In i _1-z ] O ₂ (z ≧ 0.4), the replacement of nickel by manganese makes it possible to introduce additional lithium into the crystal structure of the material. Additional lithium is doped into the transition metal layer cation sites, and Li
_{[Li x Mn z Ni 1-} x-z] material of the composition of _{O 2} is obtained. The amount of additional lithium can be varied as described in the embodiments of the present invention. The role of lithium in the transition metal layer of these materials is to stabilize the well-developed layered structure and reduce the tendency to retain transition metal cations located in the lithium layer. This is because the driving force at which the transition metal is erroneously located in the lithium layer is a function from the site entropy. In a stoichiometrically well-ordered Li [M] O ₂ material, there is a large gain in site entropy when certain Li and M exchange sites. This effect is called cation mixing. If this material has excess Li, its ideal configuration is Li [Li _x M _1-x ] O ₂ . When M occupies a Li site, {Li _{1− y My} }} [Li _{x + y} M
Sites gain resulting in _{1-x-y] O 2} is greatly reduced. In the material of the present invention, additional lithium doping of the transition metal layer results in a cathode having a very low amount of transition metal in the lithium layer and good electrochemical properties. Lithium also helps to dilute the reactive Ni ⁴⁺ , thus further improving the thermal safety properties.

In order to obtain a phase having a better layer structure
The benefits of incorporating additional lithium into the structure.
However, it can be explained in an alternative method. L
iMO ₂Material (LiCrO₂, LiAlO₂, LiMn
O₂, LiCoO₂, LiNiO₂, LiTiO₂)
Observation shows that transition metal cations are much smaller than lithium
The phase tends to develop well if it has a small ionic radius
It is in. The larger the radius of each other, the more layered
Creating phases becomes more difficult. For example, trivalent manganese
Pure LiMnO with₂Is a layered structure
Thermodynamically stable. On the other hand, lithium is converted to LiMnO₂
Always causes crystallization in the layered structure.
LiMnO₂(Otherwise, Li [Li_1/3M
n_2/3] O₂ Known as). this child
Is a lithium ion with an ionic radius of tetravalent manganese
This can be explained by the fact that it is much smaller than the radius.
Also, 1 / 3Li⁺And 2 / 3Mn⁴⁺Average ion of
The radius is still much smaller than the ionic radius of lithium.
Therefore, the layered structure is stabilized.

The concept of doping Li directly into transition metals is not a study on LiNiO ₂ . Li
The phase of [Li _1/3 Ni _2/3 ] O ₂ (where Ni is tetravalent) can be prepared under extreme oxidizing conditions. However, it is not stable at high temperatures, or lowers the oxygen partial pressure. Additional lithium can be doped into Co,
A phase with stoichiometric Li _{1 + y} Co _1-y O ₂ results. However, in this case, this doping is not advantageous. Undoped LiCoO ₂ has a complete layer structure Li
Layer Li _{1 + x} with [Co] O ₂ but rich in lithium
Co _1-x O ₂ is Li with a large cation mixture
Becomes _{1-y Co y [Li x} + y Co 1-x-y] O 2 material.

To change the transition metal layer in LiNiO ₂ -based materials, lithium doping has another advantage compared to other dopants described in the prior art. Lithium is a very light element. For many battery applications, the interest is in mass energy density or capacity. Dopants such as Al and Mg _1/2 Ti _1/2 for Ni in LiNiO ₂ are electrochemically inert. They do not change the valence state while charging and discharging the battery cathode. Their role is to improve capacity retention and safety during the cycle. In the present invention, lithium is used for the same purpose. However, after doping with lithium, the final material is LiNiO
₂ , the molecular weight per Ni is smaller. Thus, for discharge as well (for the valence state of the transition metal), the lithium-doped material has a higher weight discharge capacity.

The additional Li amount x of the material according to the invention must be at least 0.03 in order to obtain the stated advantages of lithium in the transition metal layer. However, the theoretical capacity of the material decreases with increasing lithium doping in the transition metal layer. Preferred excess lithium is in the range of 0.05 to 0.10.

According to another aspect of the present invention, the addition of Co enhances the advantage of retaining additional lithium in the transition metal layer to contribute to the improvement of the layered structure over prior art materials. Co is also known to improve electronic conductivity and ion diffusion in the layered phase. This is an additional advantage. Composition Li [Li _x C
The amount y of _{o y (Mn z Ni 1-} z) 1-x-y] O 2 of Co is small as 0.05. However, to obtain the advantages of the present invention, preferably y ≧ 0.1. On the other hand, Co
Is expensive and harmful, so y> 0.3 greatly reduces the cost and safety advantages of the materials of the present invention.

In practice, pure oxides, hydroxides or carbonates (eg Mn ₂ O ₃ , Ni (OH) ₂ , Li ₂ CO 3
_{3, Co 3 O 4)} by direct solid-state reaction from a precursor such as _{Li [Li x Co y (Mn} z N
It is very difficult to prepare a solid solution of i _1-z ) _1-xy ] O ₂ . Such a preparation would require very long reaction times and very high temperatures to complete. Moreover, the obtained cathode has very poor cycle characteristics. This preparation method can be carried out well using a method that allows good mixing of various cations on an atomic scale. Such methods include precipitation, drying, or gelling of a mixture of dissolved transition metal salts (hydroxides, carbonates, oxalates, etc.) and other methods known in the literature. Such a method is called a "soft chemical" route. A preferred method of preparing the materials of the present invention is co-precipitation of the mixed hydroxide. This is because the microstructure can be controlled. The mixed hydroxide is then sintered in a heating step with a lithium source (eg, Li ₂ CO ₃ ).

Alternatively, fully crystallized Li [Li _{x
Co y (Mn z Ni 1-} z) 1-x -y] a _{O 2} using a lithium source and mixed oxides can be prepared by a solid state reaction. The mixed oxide has a rock salt structure MO or a spinel structure M ₃ O ₄ and may be prepared by a solid state reaction or from a mixed hydroxide or other soft chemical route. It can be prepared from a precursor.

In another embodiment of the present invention, a fully layered
The material is a precursor prepared by a high energy ball mill process.
It can be obtained by sintering the body. Conventional process
Then, MO or M by ball mill₃O₄Oxide of
A transition metal precursor is prepared in the mixture. Then the transition gold
The genus precursor is mixed with a lithium source, typically a lithium salt
Then, a final sintering step is performed. In another conventional way,
The transition metal precursor is pulverized with a lithium salt and a ball mill, and
After sintering. In these conventional methods, it is sintered
Precursors should not have cations in the correct valence state
No. Another approach is to use the correct transition metal oxidation
Lithium fully mixed with the precursor material of the state
Ball mill and then sinter. According to this method,
Has a small amount of transition metal ion misplaced at the thium site
Final equilibrium for the layered phase
And more effectively achieved. This generally means that M transitions
Stoichiometric MO containing metal and lithium
Ball mixture of lithium transition metal oxides with "salt"
This can be achieved by milling. Layered phase LiCo
O ₂, LiNiO₂And Li [Li_1/3M
n_2/3] O₂And Al-doped LiMnO₂You
And LiMnO₂Is an orderly positive with the general formula MO
It can be described as an ion lock salt type oxide. M is added
Li, Ti, Mn, Ni, Fe, Co, Al and
And / or Mg. Various Types of Rock Salt Precursors L
iMO₂The use of a mixture of
The desired stoichiometric amount of Li in the salt layer_xM_1-xO (x is
About 0.5 or slightly greater than 0.5)
It is. The precursor having a controlled excess of Li is a precursor
Within Li [Li_{1 / 3}Mn_2/3] O₂And LiMnO₂
Achieved by using a balanced amount of the mixture
You. After ball milling, the disordered rock salt phase obtained
The transition metal valence state has the same stoichiometric final layering
Same as in the phase. In addition, Li is a transition metal
Mix well with on. Therefore, the final layering
The equilibrium for the phase does not require the addition of oxygen from the gas phase.
And do not require long-term cation diffusion.
No. Furthermore, the equilibration during the final sintering step is very fast.

LiMnO₂Material placed in lithium layer
It tends to have some transition metal ions that are different.
This is because site entropy contributes to free-form enthalpy.
Because I offer it. The function of this entropy depends on the temperature.
Exist. The higher the temperature, the higher the contribution. Accordingly
At high temperatures, the transition metal displaced in the lithium layer
Phase tends to be high, and lithium
Hinder the benefit of taking the system. This is a consequence of the prior art.
LiMnO₂And substituted LiMnO₂Well-known materials
It is. Therefore, from the prior art, such materials
But at relatively low temperatures and / or relatively short heating times
It can be seen that it is prepared by For example, US Pat.
According to No. 26,635 (Matsushita, 1997), Li
Ni_1-yM _yO₂Compounds react at temperatures below 800 ° C
Responded. According to this patent, Mn substituted with Ni is
When the material containing is heated above 800 ° C, Mn
Misplaced at the Li site of the structure, resulting in disorder
As a result, the discharge capacity and the cycle life are shortened. Of the present invention
An important property of a material is that
Can be sintered at a relatively high temperature (above 900 ° C)
That is. Such a sintering process is actually layered
Improve the electrochemical properties of the material of the present invention without deteriorating the structure
Good. Due to this property, the material of the present invention can be used in many conventional techniques.
Differentiated from surgical materials and this recipe.

Another advantage of the material of the present invention is that it enhances thermal safety properties. Manganese is relatively stable in tetravalent as compared to cobalt or nickel, ie,
Non-reactive. Therefore, manganese is reactive Ni
⁴⁺ by diluting a effective dopant for improving the safety of the materials based on LiMnO _2. While the prior art replaces the Al or Mg + Ti combination to achieve the same goal, in practice such dopants result in a loss of capacity and / or cathode speed capability. If the cathode has a high electronic conductivity, the diffusion of lithium will only be faster. For dopants such as Al or Mg that are stable only in certain valence states,
Manganese is stable at 3+ and 4+ valencies. Thus, manganese contributes to electronic conductivity by allowing hopping of electrons or holes. Al or Mg do not contribute as well. Therefore, higher levels of Mn doping than doping with Al or Mg can be used to effectively dilute the reactive Ni ⁴⁺ without loss of electronic conductivity. Manganese substitution of LiNiO ₂ does not theoretically reduce the maximum discharge capacity. In LiNiO ₂ , nickel is trivalent. When all lithium is extracted, one equivalent of nickel changes from a 3+ to a 4+ valence state, and the capacity is 285 m.
Ah / g. The same maximum capacity is theoretically obtained for Li [Ni _1/2 Mn _1/2 ] O ₂ . In Li [Ni _1/2 Mn _1/2 ] O ₂ , nickel is considered to be divalent and manganese is tetravalent. When all lithium is extracted, half the equivalent of nickel is 2+ to 4
Charged to the + valence state, producing the same capacitance.

Comparative Example 1 This example demonstrates that the addition of extra lithium alone to LiNiO ₂ or LiCoO ₂ does not improve the layered structure in these materials.
For Li ₂ CO ₃ and Ni (OH) ₂ , Li: Ni = 1.
05: 1 (Sample 1A) and Li: Ni = 1.25: 1
(Sample 1B) is mixed and pulverized. The resulting powder is reacted at 750 ° C. for 2 days in air.

Li ₂ CO ₃ and CoO are Li: Co =
1.05: 1 (sample 1C) and Li: Co = 1.2
Mix and grind at 5: 1 (Sample 1D). The resulting powder is reacted at 750 ° C. for 2 days in air.

The X-ray diffraction patterns (C
uk X'Pert instrument using uK radiation
FIG. 1 is shown in FIG. All materials dominantly have R-3m structure
Layered phase. Sample 1A (LiNiO₂) X-ray
The pattern is traces of Li₂CO ₃Is shown. Sample 1B
The turn is Li₂CO₃Shows an increase in the intensity peak for
You. From this, the excess lithium is converted to LiNiO₂material
It is understood that it is not taken into. This is the X-ray diffraction pattern
Confirmed by careful analysis of the sequence. The result
The results are shown in Table 1. Unit cell volume is a general formula unit
LiMO₂Given to Samples 1A and 1B
Have similar lattice constants and R values. Where the experiment
Typical R value is 006+ with respect to the integrated intensity of 101 peak.
Obtained by calculating the ratio of the integrated intensity of the 102 peaks.
It is. The R value is calculated by the following formula to the amount x of lithium in the lithium layer.
More relevant.

(Equation 1) Thus, 1-x is the number of misplaced transition metals.

Therefore, the R value is {Li _1-x Ni _x }
Enables estimation of the composition of the [Ni] O ₂ phase (see Table 1). The R values for samples 1A and 1B are both greater than or equal to 0.7, indicating that a large amount of nickel is displaced on the lithium layer. To obtain a high-rise shape of material having additional lithium in the transition metal layer, the addition of lithium is concluded that it is not effective against LiNiO _2.

Samples 1C and 1D were single phase materials. The lattice constants are the same. By careful analysis of the X-ray diffraction pattern, additional lithium is added to the LiCoO
It can be concluded that the _second transition metal layer can be incorporated. Lightly doped sample 1C (LiC
(stoichiometry close to oO ₂ ) has a highly layered structure. R
The values are close to the ideal values for a layered structure with no transition metal in the lithium layer. However, the lithium-rich sample 1D
(Almost stoichiometric amount of Li _1.11 Co _0.89 O ₂ )
Has low layering. The R value is as large as 0.7. Composition L
i _{1 + y} Co _1-y O2 and the structure {Li _1-x C
against _{o x} [Li y + x} Co 1-x-y] cathodes of _{O 2,} the following relationship is obtained.

(Equation 2)

In the case of sample 1D, LiCo rich in LiCo
O ₂ is shown to have a cobalt cation misplaced large amount on the Li layer. Its structure is ｛Li
_0.87 Co _0.13 {[Li _0.24 Co _0.76 ]
It is estimated as O _2.

Clearly, LiNiO by lithium alone
Doping with ₂ or LiCoO ₂ does not result in a layered structure. However, the examples that follow show that a layered material having Li in the transition metal layer by substitution with manganese can be obtained in the material of the invention.

[Table 1]

Examples 2 and 3 By doping the transition metal layer of the material of the invention with additional lithium, a layered material with a low concentration of transition metal ions misplaced in the lithium layer was obtained. These examples are shown. This benefit increases when the material contains Co. The amount of Co is about 10% of the total transition metal.
If it is higher than%, a highly layered structure is thermodynamically preferred. In this case, a longer reaction time allows equilibration of the material towards a highly layered structure with very few misplaced transition metals.

The mixed hydroxide [Co _x (Mn _z N)
i1 _-z ) _1-x ] _Ow (OH) _q could be prepared by coprecipitation from a Mn-Ni-Co nitrate solution using a NaOH solution. Three different mixed hydroxides were prepared with Z = about 0.5 and different Co amounts (about 5%, 10%, 16.7% of transition metal). Collect the sediment and in air 120
Dried at ° C. The precipitate was then mixed with different stoichiometric amounts of Li ₂ CO ₃ and ground. The resulting powder was reacted at 750 ° C. for 36 hours in air. The following results were obtained by chemical analysis of the final sample.

Samples 2A and 2B have the composition Li [Li _y M
It has a _{1-y] O 2,} where y = 0.095 and y =
0.134, M = Mn _0.469 Ni _0.48 Co
_0.05 was _1.

Samples 2C and 2D have the composition Li [Li _y M
It has a _{1-y] O 2,} where y = 0.083 and y =
0.123, M = Mn _0.449 Ni _0.45 Co
_0.10 was _1.

Samples 2E and 2F have the composition Li [Li _y M
It has a _{1-y] O 2,} where y = 0.064 and y =
0.106, M = Mn _0.416 Ni _0.415 Co
It was _{0.1 69.}

All samples are single phase and have a layered α-NaFe
It was an O ₂ structure. FIG. 2 shows two important areas of the X-ray pattern. The diffraction pattern becomes more regular, and as the amount of Co increases, it becomes a characteristic of a layered structure.
In particular, the separation between peaks 108 and 110 and between 006 and 102 is greater. The structural data obtained by careful analysis of the X-ray diffraction data is shown in Table 2A. Comparing the results of Samples 2A and 2B, 2C and 2D, and 2E and 2F, the second sample in each set has more Li and, for all Co doping levels, the Li-rich sample has c / a Indicates that the ratio is higher. The additionally introduced Li leads to a more complete layered structure.

Samples 2A-F are sintered for 4 days at 750 ° C. in air to obtain Samples 3A-F. All samples after sintering were single phase and had a layered α-NaFeO ₂ structure. FIG. 3 shows two important areas of the X-ray pattern.
The diffraction pattern becomes more regular, and as the amount of Co increases, it becomes a characteristic of the layered structure. In particular, 108 and 1
There is greater separation between the 10 peaks and between 006 and 102 peaks. The structural data obtained by careful analysis of the X-ray diffraction data is shown in Table 2B. Sample 3
A and 3B, 3C and 3D, and 3E and 3F
Comparing the results, the second sample in each set shows more Li and the higher Li sample has a higher c / a ratio for all Co doping levels. The additionally introduced Li leads to a more complete layered structure.

From the R value (integrated peak intensity ratio) obtained experimentally, the concentration of the misplaced transition metal cation was estimated. Stoichiometric amount of Li [Li _y M _1-y ] O ₂ , M =
_{(Ni 1/2 Mn 1/2)} 5/6 Co 1/6, materials and formula having _{{Li 1-x M x}} [Li y + x M
Against _1-y-x] cation mixture in reaching the _{O 2} (xM exchange places the x lithium), R is according to the following equation, dependent on x and y.

(Equation 3)

The results are shown in Table 3 and FIG. FIG. 4 shows that the sample containing more lithium and cobalt has a lower concentration of misplaced transition metal cations. 36
Comparing the equilibrium after time and after 5 days, it can be seen that as the level of cobalt increases, the sample equilibrates towards a layered structure with a lower concentration of misplaced transition metal cations. However, if the cobalt doping is too low (less than about 10% of the total transition metal), the equilibrium will tend toward a less stratified structure. Improvements in the Rietveld method of the X-ray diffraction data showed the same trend and similar concentrations of misplaced cations.

For all samples, as the stoichiometry of lithium and the cobalt content increase, the degree of mislocated cations tends to be lower. Doping with a sufficient amount of cobalt (≧ 10%) results in thermodynamic stabilization of the phase with very few misplaced cations. Long reaction times are required to reach this preferred equilibrium configuration.
Therefore, this example shows that a large excess of lithium (Li [Li
_x M _1-x ] O ₂ , where x is 0.11) and the long reaction time with heavy cobalt doping makes it possible to prepare samples with very small amounts (about 1%) of misplaced cations. it can.

The electrodes containing samples 3D, 2E, 2F, 3E and 3F were treated with 80% by weight of oxide material, 12% by weight of acetylene black and 8% by weight of poly (vinylidene fluoride) with 1-methyl-2- Pyrrolidinone (NM
It was prepared by mixing as a slurry of P). This slurry was coated on aluminum foil. After evaporation of the solvent, the coating was pressed on aluminum foil and annealed at 150 ° C. under vacuum. Thereafter, a ring electrode having a diameter of 14 mm was punched from the coating foil. The ring electrodes were weighed individually and the effective mass was calculated (by multiplying the total mass of the ring electrode, corrected for the weight of the aluminum substrate, by a fraction of the electrode weight made of lithiated metal oxide material). . The electrodes were then dried at 150 ° C. under vacuum to remove traces of water and dried in a glove box filled with argon (<1 pp.
m).

The electrodes were placed in an electrochemical cell in a dry glove box filled with argon, using 2032 button cell hardware, with a thickness of 0.38 m as the anode.
m lithium foil annular disk and electrode solution (50
Assembled using a porous glass transition disc separator wetted with 1M LiPF ₆ in (wt% ethylene carbonate + 50 wt% dimethylene carbonate).

The battery prepared by this method was used at room temperature (21
C.) and elevated temperature (55 ° C.) more than 200 cycles between 2.0 and 4.4V. A constant charging current was applied until reaching 4.4 V, after which the current was reduced to 15 mA /
The battery was maintained at 4.4V until it fell below g. The battery was discharged at a constant current to 2.5V. Replace the battery with 30
Charge and discharge were performed up to cycle 5 at a current rate of mA / g (C / 5 rate). After that, 75 mA / g (c
/ 2 rate).

The best electrochemical properties were obtained for material 3F. It had a reversible capacity of 155 mA / g at C / 5 rate. 139 mA capacity at C / 2 rate
/ G. After 100 cycles at C / 2 rate, 8
9% capacity was retained. After 200 cycles, 81% capacity was maintained. Sample 2F had a similar initial volume, but the volume disappeared rapidly with cycling (50
50% retention after the cycle). According to this example, a material prepared by doping the transition metal layer with sufficient lithium, additionally doping with cobalt, and prolonging the sintering time, resulting in very few misplaced cations, is excellent. This shows that a cathode having electrochemical properties can be obtained.

[Table 2]

[Table 3]

Composition Co _0.16 Mn _0.43 Ni
A mixed hydroxide of _0.41 O _w (OH) _q was prepared as described in Examples 2 and 3 and the stoichiometric ratio of Li ₂ CO ₃ and 1.1 of Li to 1 transition metal. And for two days,
The reaction was performed at 970 ° C. in the air. Table 4 shows the crystal structure data.
Shown in A cathode made of the material was prepared, and Example 2 was prepared.
And 3 as described. At 22 ° C., the material exhibited a 167 mA / g capacity in 16 cycles (where the current rate was 30 mA / g) and a 150 mA / g capacity in 18 cycles (where the current rate was 150 mA / g). g). Over 100 cycles,
Loss of capacity was less than 4%. Cycle 196 (3
(0 mA / g), the discharge capacity was 161 mA / g. Thus, the material exhibited high capacity, rate capacity and capacity retention. This is related to the layered structure and to the beneficial effects on the microstructure using relatively long sintering times at high temperatures.

[Table 4]

Example 5 In this example, the material of the present invention uses a lithium source of M ₃ O
It is shown that additional lithium can be prepared by reacting a precursor having a type ₄ spinel structure and by reacting a precursor of a composition Li _{1 + x} MO ₂ having a layered NaFeO ₂ structure.

M₃O₄(Where M = (Ni_1/2Mn
_1/2)_5/6Co_1/6) Are described in Examples 2 and 3.
The mixed hydroxide (Ni_1/2M
n_{1 / 2})_5/6Co_1/6From this hydroxide for 2 days
Prepared by heating in air at 1000.degree.
M₃O₄Compound Li₂CO₃And the indicated composition Li
[Li_xM_1-x] O₂(X = 0.11) was obtained. mixture
The powder was reacted for 5 days at 750 ° C. in air, and sample 5A
I got Example 4 material with additional Li₂CO ₃Mixed with
And the display composition Li [Li_xM_1-x] O₂(Y = 0.1
1) was obtained and reacted in air at 750 ° C for 5 days.
5B was obtained. The material of Example 4 is replaced with additional Li₂CO₃
With the indicated composition Li [Li_xM_1-x] O₂(Y =
0.09) and reacted in air at 750 ° C for 5 days
Then, Sample 5C was obtained. FIG. 5 shows the precursor and final phase 5A.
5A and 5B show diffraction patterns. Sample 5C is sample 5B
A pattern similar to the pattern shown in FIG. α-NaFeO
₂Single-phase highly layered Li [Li_xM_1-x] O
₂Was obtained in all cases. Samples 5B and 5C
It is more crystallized than sample 5C. This is the stress
To show the broadening of the peak. For samples 5B and 5C
The diffraction pattern is 20-22 degrees 2θ and the intensity of sample 5A
Than Li [Li_xM_1-x] O₂
That the additional Li of the transition metal layer of
Show.

Table 5 shows the structural data for these samples. All samples are stratified and have a high c / a ratio. However, due to the higher c / a and smaller R factor for sample 5A, it can be seen that it has a slightly better lamellar structure than sample 5B or 5C. M =
The relationship between R, x, and y for (Ni _1/2 Mn _1/2 ) _5/6 Co _1/6 is as follows.

(Equation 4)

Using the experimental R values obtained from the integrated intensities of the peaks at 101, 102, and 006, the structure of sample 5A was changed to {Li _0.971 M _0.029 } [Li _0.14
M _{0 . 86]} is calculated as _{O 2.} The structure of sample 5B was changed to {Li _0.971 M _0.029 } [Li _0.14 M
_0.86] is calculated as _{O 2.} The structure of sample 5C is expressed as
i _{0 . 97} M _0.03 {[Li
_0.121 M _0.879] calculated as _{O 2.} Good electrochemical properties are obtained due to the low concentration of misplaced transition metal cations on the lithium layer. Cathodes with samples 5B or 5C were prepared and tested using methods as described in Examples 2 and 3. And, excellent electrochemical properties are shown in Table 6. C / 5, C
FIG. 6 shows the discharge voltage characteristics of the sample 5C battery as a cathode at the / 2, C, and 2C rates.

[Table 5]

[Table 6]

Example 6 This example shows that the materials of the present invention can also be synthesized from precursors prepared by a high energy ball mill. This example focuses specifically on the preparation of a rock salt type precursor by ball milling. This precursor contains all cations, including oxygen and the desired stoichiometric ratio of lithium, and is well-mixed on an atomic scale.
The final reaction leading to the layered phase does not require long-term cation or oxygen diffusion. Therefore, the process is quick and the reaction time is shortened.

The preparation was performed in two steps. That is, an oxide of the Rock salt type is prepared using a high energy ball mill with well-mixed oxygen and cations (including lithium) on an atomic scale; Obtain a layered phase.

Li₂MnO₃(That is, Li [Li
_1/3Mn_2/3] O₂), Li [Ni _0.8Co
_0.2] O₂, And LiCoO₂Powder in air
Prepared by conventional solid state reaction. LiMnO₂The traditional
The solid state reaction of₂Prepared in stream. As a receptor
Al₂O₃It was used.

Li [Li _1/3 Mn _2/3 ] O ₂ , Li
[Ni _0.8 Co _0.2 ] O ₂ , and LiMnO ₂ ,
And Al ₂ O ₃ powder are mixed to give the indicated stoichiometry Li
[Li _0.05 Mn _0.37 Ni _0.37 Co _0.14
Al _0.07 ] O _2.035 was obtained. A small excess of oxygen can indeed result in a mixed oxide of the rock salt type (stoichiometric MO, where M = Li _0.525 Mn) in a ball mill.
_0.185 Ni _0.185 Co _0.07 A
l _0.035 ). A in FIG.
5 shows an X-ray diffraction pattern after performing ball milling for 5 hours. The peaks in the diffraction pattern are broad and show very small grains. The crystal structure is predominantly disordered rock salt MO, but with a low degree of transition metal order (perhaps low temperature LiCoO ₂
In a cubic spinel-type structure known to
Is indicated by the peak at 18.5 degrees 2θ.

The ball milled powder was subjected to a heat treatment at 800 ° C. for 24 hours without the addition of additional lithium. The X-ray diffraction pattern of the final material is shown in FIG. This material contains a very small amount of impurities, indicated by a small shoulder peak at 43.7 degrees 2θ. However, the main phase is a single phase having the desired layered NaFeO ₂ structure. The hexagonal c-axis is 14.283 ± 0.
0015, the a-axis is 2.874 ± 0.0002 °, and the c: a ratio is 1.0144.

Example 7 In this example, the material of the present invention was prepared using commercially available LiCoO₂
And LiNiO doped with Co-Mg-Ti₂Than
Also indicates that it is more secure. LiCoO₂And C
LiNiO doped with o-Mg-Ti₂Dope
Not LiNiO ₂Known to be much more secure than
ing. In this embodiment, Li is added to the transition metal layer of the present invention.
An important advantage of Mn substitution caused by the addition is that
It is shown that the goal is to obtain a cathode with improved integrity.

The cathode was made of a commercially available LiCoO₂Material (B
ET surface area 0.48m²/ G), commercially available LiNi_0.7
Co_0.2Ti_0.05Mg_0.04O₂(BET surface
1.9m product²/ G), and sample 5BLi of Example 5.
[Li_0.11M_0.89] O ₂, Where M = (Ni
_1/2Mn_1/2)_5/6Co_1/6, (BET surface area
1.3m²/ G). Make the cathode
To make the slurry, Super S carbon (70mg)
And a well shaken mixture of 700 mg cathode
Mixed with 250 mg of DBP (dibutyl phthalate)
180 mg of dissolved in 2.2 g of dry acetone
Solution consisting of 8 Kynarflex copolymer
It was prepared by adding to the solution. This slurry
Use a doctor blade on the tape
Struck. After drying, the sheet was dried with anhydrous ethyl ether.
Washed three times to remove DBP. After that, the cathode
The punch was punched. The battery was described in Example 3.
Prepared similarly. However, EC / DEC (50/5
0 ratio) as an electrolytic solvent instead of EC / DMC
did.

The battery containing LiCoO ₂ was charged, discharged, and recharged to 4.2V. LiNi _0.7 Co
_3. A battery containing _0.2 Ti _0.05 Mg _0.04 O ₂ .
Charged to 3V and 4.5V, Li [Li _0.11 M
_0.89 ] O ₂ (M = {Ni _1/2 Mn _1/2 } _5/6
Co _1/6 ) was charged to 4.3V, 4.4V and 4.5V. The current corresponded to the C / 15 rate. The cell was maintained at the high voltage for about 2 hours. FIG. 8 shows the electrochemical charging before the DSC measurement. Table 7 shows the charging capacity for recharging.

The battery was opened in an argon-filled glove box, taking care not to short-circuit the battery. The cathode was removed and dried for about 1 minute. Thereafter, half of each electrode was placed in a small DSC-aluminum can and crimped air tight. The aluminum can was removed from the glove box and differential scanning calorimetry (DSC) measurements were performed in a stream of argon using a ramp of 5 K / min. FIG. 9 shows the result.

All materials show an exothermic reaction. Heat dissipation at high temperature
Less indicates a greater safety. LiCoO₂You
And LiNi_0.7Co_0.2Ti_0.05Mg
_0.04O ₂Is T = 220 to 240 ° C. and T = 200
It shows heat generation at temperatures of up to 240 ° C. Li charged
CoO₂Are obtained from the literature (DD Mc
Neil, J .; R. Dahn)
You. The material of the present invention, Li [Li
_0.11M_0.89] O₂Is 30 depending on the charging depth
A single thermal change is indicated from 0 to 320. Overcharge cathode
(4.5V) even at a high temperature of 300 ° C, the first
Indicates fever. LiCoO₂And LiNi_0.7Co
_0.2Ti_{0. 05}Mg_0.04O₂Compared to
Emits less heat at higher temperatures. The result is
It is shown in Table 7. Li is large and the manganese substitution material Li [Li
_xM_{1- x}] O₂Greatly improves the safety characteristics.

[Table 7]

The above description is merely for explaining the present invention and does not limit the present invention.

[Brief description of the drawings]

FIG. 1 (B) LiC “rich in lithium” of Comparative Example 1
X-ray diffraction patterns of oO ₂ samples 1C and 1D and (A) “Lithium rich” LiNiO ₂ samples 1A and 1B.

FIG. 2 is an X-ray diffraction pattern of Samples 2A-F prepared as described in Example 2.

FIG. 3 is an X-ray diffraction pattern of Samples 3A-F prepared as described in Example 3.

FIG. 4. As described in Examples 2 and 3,
Li [LiyM1- as a function of y and cobalt content
_{y] O 2 (M = (} Mn 1/2 Ni 1/2) 1-x C
Concentration of misplaced cations in o _x).

FIG. 5. Final Li [Li _y M _1-y ] O ₂ (M = (N
i _1/2 Mn _1/2 ) _5/6 Co _1/6 , y = 0.1
1) X-ray diffraction pattern (insert materials 5A and 5B and precursors is an enlarged view of a region 35 to 46 degrees with respect to a phase having a layered NaFeO ₂ structure).

FIG. 6 shows discharge voltage characteristics of sample 5C for different rates.

FIG. 7: (B) Final material Li [Li _0.05 Mn _0.37 N, prepared as described in Example 6.
i _0.37 Co _0.14 Al _0.07 ] O ₂ , and (A) a rock salt precursor Li ground by a ball mill
_0.525 Mn _{0.18 5} Ni _0.185 Co _0.07
X-ray diffraction pattern of Al _0.035 O.

FIG. 8: LiCoO ₂ , L of Example 7 before DSC measurement
iNi _0.7 Co _0.2 Ti _0.05 Mg _0.04 O ₂
And Li [Li _0.11 M _0.89 ] O ₂ cathode charging regime.

9: 4.3, 4.4 and 4. described in Example 7. FIG.
Li [Li _0.11 M _0.89 ] O ₂ charged to 5V
Commercial Li charged to 4.3 V and 4.5 V for (M = Ni _1/2 Mn _1/2 ) _5/6 Co _1/6 )
Ni _0.7 Co _{0 .} Commercial LiCoO for ₂ Ti _0.05 Mg _0.04 O ₂ and charged to 4.2 V
DSC results for ₂ .

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Jens Martin Poulsen New Zealand Manukau Clover Park Changti Avenue 1/43 (72) Inventor Lone Yen Kiew Auckland Mount Wellington Waters Road 11 (72) New Zealand Inventor Brett Graeme Ammunsen New Zealand Auckland Archhill Brisbane Street 22 F-term (reference) 4G048 AA04 AB02 AC06 AC08 AD06 AE05 5H029 AJ03 AJ05 AJ12 AK03 AL06 AL12 AM03 AM05 AM07 CJ02 CJ08 CJ28 DJ17 EJ01 HJAJAJ EJ01 AJAJAJ EJ04 CA08 CA09 CB12 EA08 EA23 FA19 GA02 GA05 GA10 GA27 HA02 HA14 HA20

Claims (39)

[Claims] 1. A single-phase cathode material used in an electrochemical cell represented by the following general formula: Li in _{[Li x Co y A 1-} x-y] O 2 ( wherein, A represents a _{[Mn z Ni 1-z]} , x is about 0.
Represents a numerical value in the range of about 00 to about 0.16, and y is about 0.1 to about 0.16.
Represents a numerical value in the range of about 0.30, and z is about 0.40 to about 0.3
It represents a numerical value in the range of 65, and Li _x is included in the transition metal layer of the structure. ) 2. The method of claim 1, wherein the material has a c greater than about 1.012.
The material of claim 1, comprising a layered R-3m crystal structure having a / a ratio. 3. The material of claim 1, wherein x represents a number in the range from about 0.05 to about 0.10. 4. The material of claim 1, wherein y represents a value of about 0.16. 5. The material of claim 1, wherein z represents a value of about 0.50. 6. x represents a number in the range of about 0.05 to about 0.10, y represents a number of about 0.16, and z represents a number of about 0.50. The material of claim 1. 7. A single-phase cathode material used in an electrochemical cell represented by the following general formula: Li in _{[Li x Co y A 1-} x-y] O 2 ( _{wherein, A = [Mn z Ni 1} -z] represents; x is about 0.
Represents a number in the range of 0 to about 0.16; y is about 0.1 to about 0.16
Represents a number in the range of 0.30; z is about 0.40 to about 0.6
Represents 5 range of numerical values; Li _x is included in transition metal layers of the structure; and / or wherein the material of about 1.012
It comprises a layered R-3m crystal structure with a larger c / a ratio. ) 8. The material of claim 7, wherein x represents a number in the range from about 0.05 to about 0.10. 9. The material of claim 7, wherein y represents a value of about 0.16. 10. The material of claim 7, wherein z represents a value of about 0.50. 11. x is a number in the range of about 0.05 to about 0.10, y is a number in the range of about 0.16, and z is a number in the range of about 0.50. The material according to claim 7. 12. A system comprising a current collector and a cathode active material applied to the current collector.
An electrode used in an electrochemical cell, wherein the active material is represented by the following general formula. Li in _{[Li x Co y A 1-} x-y] O 2 ( _{wherein, A = [Mn z Ni 1} -z] represents; x is about 0.
Represents a number in the range of 0 to about 0.16; y is about 0.1 to about 0.16
Represents a number in the range of 0.30; z is about 0.4 to about 0.65
And Li _x is included in the transition metal layer of the structure. ) 13. The electrode of claim 12, wherein said material comprises a layered R-3m crystal structure having a c / a ratio greater than about 1.012. 14. The electrode according to claim 12, wherein x represents a numerical value in a range from about 0.05 to about 0.10. 15. The electrode according to claim 12, wherein y represents a numerical value of about 0.16. 16. The electrode according to claim 12, wherein z represents a value of about 0.50. 17. x represents a number in the range of about 0.05 to about 0.10, y represents a number of about 0.16, and z represents a number of about 0.50. An electrode according to claim 12. 18. An electrochemical cell comprising an electrolyte, an anode electrode, and a cathode electrode, said cathode electrode comprising a current collector and a cathode active material applied to said current collector, wherein said electrochemical cell comprises: An electrochemical cell in which the active material is represented by the following general formula: Li in _{[Li x Co y A 1-} x-y] O 2 ( _{wherein, A = [Mn z Ni 1} -z] represents; x is about 0.
Represents a number in the range of 0 to about 0.16; y is about 0.1 to about 0.16
Represents a number in the range of 0.30; z is about 0.4 to about 0.65
Li _x is included in the transition metal layer of the structure. ) 19. The electrochemical cell of claim 18, wherein said material comprises a layered R-3m crystal structure having a c / a ratio of about 1.012. 20. The electrochemical cell according to claim 18, wherein x represents a number in the range of about 0.05 to about 0.10. 21. The electrochemical cell according to claim 18, wherein y represents a value of about 0.16. 22. The electrochemical cell according to claim 18, wherein z represents a value of about 0.50. 23. x represents a numerical value in the range of about 0.05 to about 0.10, y represents a numerical value of about 0.16, and z represents a numerical value of about 0.50. An electrochemical cell according to claim 18. 24. The electrochemical cell according to claim 18, wherein said anode electrode comprises a lithium intercalation anode. 25. The electrochemical cell according to claim 18, wherein the electrolyte comprises a non-aqueous electrolyte containing a lithium salt. 26. A method of making a single-phase cathode material for use in an electrochemical cell represented by the general formula: preparing a precursor having a mixture of Ni, Mn, and Co cations. And mixing the precursor with a stoichiometric amount of a Li source and reacting the resulting mixture at an elevated temperature. Li in _{[Li x Co y A 1-} x-y] O 2 ( _{wherein, A = [Mn z Ni 1} -z] represents; x is about 0.
Represents a number in the range of 0 to about 0.16; y is about 0.1 to about 0.16
Represents a number in the range of 0.30; z is about 0.4 to about 0.65
And Li _x is included in the transition metal layer of the structure, and / or the material is about 1.01.
It comprises a layered R-3m crystal structure having a c / a ratio greater than 2. ) 27. The method of claim 26, wherein the step of providing a precursor comprises the step of providing a mixed metal hydroxide. 28. The method of providing a precursor, comprising the steps of:
27. Providing a mixed metal hydroxide obtained from coprecipitation of a solution containing a mixture of n and Co.
The described method. 29. The step of supplying a precursor comprises the step of reacting a compound of the general formula M ₃
O ₄ (wherein, M is Ni, Mn, and. That represents the combination of Co) The method of claim 26 further comprising the step of supplying a mixed metal oxide represented by. 30. The step of supplying a precursor comprises the step of formula (MO)
28. The method of claim 26, comprising providing a mixed metal oxide represented by the formula: wherein M represents a combination of Ni, Mn, and Co. 31. The step of supplying a precursor comprises the step of reacting with a general formula Li
_x MO ₂ (where, M is Ni, Mn, and Co represents a combination of, x is. representing about 1) The method of claim 26 further comprising the step of supplying a mixed metal oxide represented by. 32. The method of claim 26, wherein supplying the precursor comprises heating the precursor in an oxygen containing atmosphere at a temperature ranging from about 500 ° C to about 1000 ° C. 33. The method of claim 26, wherein supplying the precursor comprises heating the precursor in an oxygen-containing atmosphere at a temperature ranging from about 900 ° C to about 1000 ° C. 34. The method of claim 1, wherein the reaction at elevated temperatures is at least one.
27. The method of claim 26, which is performed for 2 hours. 35. A method for producing a single-phase cathode material used in an electrochemical cell represented by the following general formula, comprising the steps of: preparing a metal oxide powder containing Ni, Mn, Co, and Li; Mixing and milling the mixture with a ball mill to obtain a precursor oxide, and heating the precursor oxide. Li in _{[Li x Co y A 1-} x-y] O 2 ( _{wherein, A = [Mn z Ni 1} -z] represents; x is about 0.
Represents a number in the range of 0 to about 0.16; y is about 0.1 to about 0.16
Represents a number in the range of 0.30; z is about 0.4 to about 0.65
And Li _x is included in the transition metal layer of the structure, and / or the material is about 1.01.
It comprises a layered R-3m crystal structure having a c / a ratio greater than 2. ) 36. The step of mixing a metal oxide powder,
36. The method of claim 35, comprising the step of mixing the metal oxide powder to such an extent that the total lithium and oxygen content has the approximate stoichiometry required for the final lithiated oxide material. 37. The method of claim 35, wherein the step of heating the precursor oxide occurs at a temperature ranging from about 500 ° C. to about 1000 ° C. in an oxygen containing atmosphere. 38. The method of claim 35, wherein the step of heating the precursor oxide occurs in an oxygen containing atmosphere at a temperature ranging from about 900 ° C. to about 1000 ° C. 39. The reaction at elevated temperatures wherein at least one
The method of claim 35, wherein the method is performed for 2 hours.